Restricting Relayers

While the security in AWM and Interchain Messaging doesn't rely at all on the relayer, there might be reasons why you would want to restrict the delivery of a message to certain relayers.

The most common reason is when you run your own relayer and don't want to incentivize others — you can ensure that only your relayer delivers your messages.

How Allowed Relayers Work

Let's look at the TeleporterMessageInput structure used when calling sendCrossChainMessage:

struct TeleporterMessageInput {
    bytes32 destinationBlockchainID;
    address destinationAddress;
    TeleporterFeeInfo feeInfo;
    uint256 requiredGasLimit;
    address[] allowedRelayerAddresses;
    bytes message;
}

interface ITeleporterMessenger {
    function sendCrossChainMessage(TeleporterMessageInput calldata messageInput)
        external
        returns (bytes32);
}

The allowedRelayerAddresses field lets you specify which relayers are permitted to deliver your message.

Open Delivery (Default)

Setting allowedRelayerAddresses to an empty array means any relayer can pick up and deliver the message. This is the default and most common approach:

messenger.sendCrossChainMessage(
    TeleporterMessageInput({
        destinationBlockchainID: 0x9f3be606497285d0ffbb5ac9ba24aa60346a9b1812479ed66cb329f394a4b1c7,
        destinationAddress: destinationAddress,
        feeInfo: TeleporterFeeInfo({feeTokenAddress: address(0), amount: 0}),
        requiredGasLimit: 100000,
        allowedRelayerAddresses: new address[](0),
        message: abi.encode(message)
    })
);

Restricted Delivery

To restrict delivery to a specific relayer, add its reward address to the array. A relayer is identified by the reward address it associates when delivering messages:

messenger.sendCrossChainMessage(
    TeleporterMessageInput({
        destinationBlockchainID: 0x9f3be606497285d0ffbb5ac9ba24aa60346a9b1812479ed66cb329f394a4b1c7,
        destinationAddress: destinationAddress,
        feeInfo: TeleporterFeeInfo({feeTokenAddress: address(0), amount: 0}),
        requiredGasLimit: 100000,
        allowedRelayerAddresses: [0x321f6B73b6dFdE5C73731C39Fd9C89c7788D5EBc],
        message: abi.encode(message)
    })
);

When to Restrict

Scenario	Approach
Testing / development	Open (empty array) — any relayer is fine
Running your own relayer	Restrict to your relayer's address
Privacy-sensitive messages	Restrict to trusted relayer(s)
Production with fee incentives	Open — let the fee market decide

How Allowed Relayers Work

Open Delivery (Default)

Restricted Delivery

When to Restrict

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